fs/cachefiles/bind.c - third_party/linux - Git at Google

 /* Bind and unbind a cache from the filesystem backing it
  *
  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
  * Written by David Howells (dhowells@redhat.com)
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public Licence
  * as published by the Free Software Foundation; either version
  * 2 of the Licence, or (at your option) any later version.
  */

 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/sched.h>
 #include <linux/completion.h>
 #include <linux/slab.h>
 #include <linux/fs.h>
 #include <linux/file.h>
 #include <linux/namei.h>
 #include <linux/mount.h>
 #include <linux/statfs.h>
 #include <linux/ctype.h>
 #include <linux/xattr.h>
 #include "internal.h"

 static int cachefiles_daemon_add_cache(struct cachefiles_cache *caches);

 /*
  * bind a directory as a cache
  */
 int cachefiles_daemon_bind(struct cachefiles_cache *cache, char *args)
 {
 	_enter("{%u,%u,%u,%u,%u,%u},%s",
 	       cache->frun_percent,
 	       cache->fcull_percent,
 	       cache->fstop_percent,
 	       cache->brun_percent,
 	       cache->bcull_percent,
 	       cache->bstop_percent,
 	       args);

 	/* start by checking things over */
 	ASSERT(cache->fstop_percent >= 0 &&
 	       cache->fstop_percent < cache->fcull_percent &&
 	       cache->fcull_percent < cache->frun_percent &&
 	       cache->frun_percent  < 100);

 	ASSERT(cache->bstop_percent >= 0 &&
 	       cache->bstop_percent < cache->bcull_percent &&
 	       cache->bcull_percent < cache->brun_percent &&
 	       cache->brun_percent  < 100);

 	if (*args) {
 		pr_err("'bind' command doesn't take an argument\n");
 		return -EINVAL;
 	}

 	if (!cache->rootdirname) {
 		pr_err("No cache directory specified\n");
 		return -EINVAL;
 	}

 	/* don't permit already bound caches to be re-bound */
 	if (test_bit(CACHEFILES_READY, &cache->flags)) {
 		pr_err("Cache already bound\n");
 		return -EBUSY;
 	}

 	/* make sure we have copies of the tag and dirname strings */
 	if (!cache->tag) {
 		/* the tag string is released by the fops->release()
 		 * function, so we don't release it on error here */
 		cache->tag = kstrdup("CacheFiles", GFP_KERNEL);
 		if (!cache->tag)
 			return -ENOMEM;
 	}

 	/* add the cache */
 	return cachefiles_daemon_add_cache(cache);
 }

 /*
  * add a cache
  */
 static int cachefiles_daemon_add_cache(struct cachefiles_cache *cache)
 {
 	struct cachefiles_object *fsdef;
 	struct path path;
 	struct kstatfs stats;
 	struct dentry *graveyard, *cachedir, *root;
 	const struct cred *saved_cred;
 	int ret;

 	_enter("");

 	/* we want to work under the module's security ID */
 	ret = cachefiles_get_security_ID(cache);
 	if (ret < 0)
 		return ret;

 	cachefiles_begin_secure(cache, &saved_cred);

 	/* allocate the root index object */
 	ret = -ENOMEM;

 	fsdef = kmem_cache_alloc(cachefiles_object_jar, GFP_KERNEL);
 	if (!fsdef)
 		goto error_root_object;

 	ASSERTCMP(fsdef->backer, ==, NULL);

 	atomic_set(&fsdef->usage, 1);
 	fsdef->type = FSCACHE_COOKIE_TYPE_INDEX;

 	_debug("- fsdef %p", fsdef);

 	/* look up the directory at the root of the cache */
 	ret = kern_path(cache->rootdirname, LOOKUP_DIRECTORY, &path);
 	if (ret < 0)
 		goto error_open_root;

 	cache->mnt = path.mnt;
 	root = path.dentry;

 	/* check parameters */
 	ret = -EOPNOTSUPP;
 	if (d_is_negative(root) ||
 	    !d_backing_inode(root)->i_op->lookup ||
 	    !d_backing_inode(root)->i_op->mkdir ||
 	    !(d_backing_inode(root)->i_opflags & IOP_XATTR) ||
 	    !root->d_sb->s_op->statfs ||
 	    !root->d_sb->s_op->sync_fs)
 		goto error_unsupported;

 	ret = -EROFS;
 	if (root->d_sb->s_flags & MS_RDONLY)
 		goto error_unsupported;

 	/* determine the security of the on-disk cache as this governs
 	 * security ID of files we create */
 	ret = cachefiles_determine_cache_security(cache, root, &saved_cred);
 	if (ret < 0)
 		goto error_unsupported;

 	/* get the cache size and blocksize */
 	ret = vfs_statfs(&path, &stats);
 	if (ret < 0)
 		goto error_unsupported;

 	ret = -ERANGE;
 	if (stats.f_bsize <= 0)
 		goto error_unsupported;

 	ret = -EOPNOTSUPP;
 	if (stats.f_bsize > PAGE_SIZE)
 		goto error_unsupported;

 	cache->bsize = stats.f_bsize;
 	cache->bshift = 0;
 	if (stats.f_bsize < PAGE_SIZE)
 		cache->bshift = PAGE_SHIFT - ilog2(stats.f_bsize);

 	_debug("blksize %u (shift %u)",
 	       cache->bsize, cache->bshift);

 	_debug("size %llu, avail %llu",
 	       (unsigned long long) stats.f_blocks,
 	       (unsigned long long) stats.f_bavail);

 	/* set up caching limits */
 	do_div(stats.f_files, 100);
 	cache->fstop = stats.f_files * cache->fstop_percent;
 	cache->fcull = stats.f_files * cache->fcull_percent;
 	cache->frun  = stats.f_files * cache->frun_percent;

 	_debug("limits {%llu,%llu,%llu} files",
 	       (unsigned long long) cache->frun,
 	       (unsigned long long) cache->fcull,
 	       (unsigned long long) cache->fstop);

 	stats.f_blocks >>= cache->bshift;
 	do_div(stats.f_blocks, 100);
 	cache->bstop = stats.f_blocks * cache->bstop_percent;
 	cache->bcull = stats.f_blocks * cache->bcull_percent;
 	cache->brun  = stats.f_blocks * cache->brun_percent;

 	_debug("limits {%llu,%llu,%llu} blocks",
 	       (unsigned long long) cache->brun,
 	       (unsigned long long) cache->bcull,
 	       (unsigned long long) cache->bstop);

 	/* get the cache directory and check its type */
 	cachedir = cachefiles_get_directory(cache, root, "cache");
 	if (IS_ERR(cachedir)) {
 		ret = PTR_ERR(cachedir);
 		goto error_unsupported;
 	}

 	fsdef->dentry = cachedir;
 	fsdef->fscache.cookie = NULL;

 	ret = cachefiles_check_object_type(fsdef);
 	if (ret < 0)
 		goto error_unsupported;

 	/* get the graveyard directory */
 	graveyard = cachefiles_get_directory(cache, root, "graveyard");
 	if (IS_ERR(graveyard)) {
 		ret = PTR_ERR(graveyard);
 		goto error_unsupported;
 	}

 	cache->graveyard = graveyard;

 	/* publish the cache */
 	fscache_init_cache(&cache->cache,
 			   &cachefiles_cache_ops,
 			   "%s",
 			   fsdef->dentry->d_sb->s_id);

 	fscache_object_init(&fsdef->fscache, NULL, &cache->cache);

 	ret = fscache_add_cache(&cache->cache, &fsdef->fscache, cache->tag);
 	if (ret < 0)
 		goto error_add_cache;

 	/* done */
 	set_bit(CACHEFILES_READY, &cache->flags);
 	dput(root);

 	pr_info("File cache on %s registered\n", cache->cache.identifier);

 	/* check how much space the cache has */
 	cachefiles_has_space(cache, 0, 0);
 	cachefiles_end_secure(cache, saved_cred);
 	return 0;

 error_add_cache:
 	dput(cache->graveyard);
 	cache->graveyard = NULL;
 error_unsupported:
 	mntput(cache->mnt);
 	cache->mnt = NULL;
 	dput(fsdef->dentry);
 	fsdef->dentry = NULL;
 	dput(root);
 error_open_root:
 	kmem_cache_free(cachefiles_object_jar, fsdef);
 error_root_object:
 	cachefiles_end_secure(cache, saved_cred);
 	pr_err("Failed to register: %d\n", ret);
 	return ret;
 }

 /*
  * unbind a cache on fd release
  */
 void cachefiles_daemon_unbind(struct cachefiles_cache *cache)
 {
 	_enter("");

 	if (test_bit(CACHEFILES_READY, &cache->flags)) {
 		pr_info("File cache on %s unregistering\n",
 			cache->cache.identifier);

 		fscache_withdraw_cache(&cache->cache);
 	}

 	dput(cache->graveyard);
 	mntput(cache->mnt);

 	kfree(cache->rootdirname);
 	kfree(cache->secctx);
 	kfree(cache->tag);

 	_leave("");
 }
	/* Bind and unbind a cache from the filesystem backing it
	*
	* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
	* Written by David Howells (dhowells@redhat.com)
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of the GNU General Public Licence
	* as published by the Free Software Foundation; either version
	* 2 of the Licence, or (at your option) any later version.
	*/

	#include <linux/module.h>
	#include <linux/init.h>
	#include <linux/sched.h>
	#include <linux/completion.h>
	#include <linux/slab.h>
	#include <linux/fs.h>
	#include <linux/file.h>
	#include <linux/namei.h>
	#include <linux/mount.h>
	#include <linux/statfs.h>
	#include <linux/ctype.h>
	#include <linux/xattr.h>
	#include "internal.h"

	static int cachefiles_daemon_add_cache(struct cachefiles_cache *caches);

	/*
	* bind a directory as a cache
	*/
	int cachefiles_daemon_bind(struct cachefiles_cache cache, char args)
	{
	_enter("{%u,%u,%u,%u,%u,%u},%s",
	cache->frun_percent,
	cache->fcull_percent,
	cache->fstop_percent,
	cache->brun_percent,
	cache->bcull_percent,
	cache->bstop_percent,
	args);

	/* start by checking things over */
	ASSERT(cache->fstop_percent >= 0 &&
	cache->fstop_percent < cache->fcull_percent &&
	cache->fcull_percent < cache->frun_percent &&
	cache->frun_percent < 100);

	ASSERT(cache->bstop_percent >= 0 &&
	cache->bstop_percent < cache->bcull_percent &&
	cache->bcull_percent < cache->brun_percent &&
	cache->brun_percent < 100);

	if (*args) {
	pr_err("'bind' command doesn't take an argument\n");
	return -EINVAL;
	}

	if (!cache->rootdirname) {
	pr_err("No cache directory specified\n");
	return -EINVAL;
	}

	/* don't permit already bound caches to be re-bound */
	if (test_bit(CACHEFILES_READY, &cache->flags)) {
	pr_err("Cache already bound\n");
	return -EBUSY;
	}

	/* make sure we have copies of the tag and dirname strings */
	if (!cache->tag) {
	/* the tag string is released by the fops->release()
	* function, so we don't release it on error here */
	cache->tag = kstrdup("CacheFiles", GFP_KERNEL);
	if (!cache->tag)
	return -ENOMEM;
	}

	/* add the cache */
	return cachefiles_daemon_add_cache(cache);
	}

	/*
	* add a cache
	*/
	static int cachefiles_daemon_add_cache(struct cachefiles_cache *cache)
	{
	struct cachefiles_object *fsdef;
	struct path path;
	struct kstatfs stats;
	struct dentry graveyard, cachedir, *root;
	const struct cred *saved_cred;
	int ret;

	_enter("");

	/* we want to work under the module's security ID */
	ret = cachefiles_get_security_ID(cache);
	if (ret < 0)
	return ret;

	cachefiles_begin_secure(cache, &saved_cred);

	/* allocate the root index object */
	ret = -ENOMEM;

	fsdef = kmem_cache_alloc(cachefiles_object_jar, GFP_KERNEL);
	if (!fsdef)
	goto error_root_object;

	ASSERTCMP(fsdef->backer, ==, NULL);

	atomic_set(&fsdef->usage, 1);
	fsdef->type = FSCACHE_COOKIE_TYPE_INDEX;

	_debug("- fsdef %p", fsdef);

	/* look up the directory at the root of the cache */
	ret = kern_path(cache->rootdirname, LOOKUP_DIRECTORY, &path);
	if (ret < 0)
	goto error_open_root;

	cache->mnt = path.mnt;
	root = path.dentry;

	/* check parameters */
	ret = -EOPNOTSUPP;
	if (d_is_negative(root) \|\|
	!d_backing_inode(root)->i_op->lookup \|\|
	!d_backing_inode(root)->i_op->mkdir \|\|
	!(d_backing_inode(root)->i_opflags & IOP_XATTR) \|\|
	!root->d_sb->s_op->statfs \|\|
	!root->d_sb->s_op->sync_fs)
	goto error_unsupported;

	ret = -EROFS;
	if (root->d_sb->s_flags & MS_RDONLY)
	goto error_unsupported;

	/* determine the security of the on-disk cache as this governs
	* security ID of files we create */
	ret = cachefiles_determine_cache_security(cache, root, &saved_cred);
	if (ret < 0)
	goto error_unsupported;

	/* get the cache size and blocksize */
	ret = vfs_statfs(&path, &stats);
	if (ret < 0)
	goto error_unsupported;

	ret = -ERANGE;
	if (stats.f_bsize <= 0)
	goto error_unsupported;

	ret = -EOPNOTSUPP;
	if (stats.f_bsize > PAGE_SIZE)
	goto error_unsupported;

	cache->bsize = stats.f_bsize;
	cache->bshift = 0;
	if (stats.f_bsize < PAGE_SIZE)
	cache->bshift = PAGE_SHIFT - ilog2(stats.f_bsize);

	_debug("blksize %u (shift %u)",
	cache->bsize, cache->bshift);

	_debug("size %llu, avail %llu",
	(unsigned long long) stats.f_blocks,
	(unsigned long long) stats.f_bavail);

	/* set up caching limits */
	do_div(stats.f_files, 100);
	cache->fstop = stats.f_files * cache->fstop_percent;
	cache->fcull = stats.f_files * cache->fcull_percent;
	cache->frun = stats.f_files * cache->frun_percent;

	_debug("limits {%llu,%llu,%llu} files",
	(unsigned long long) cache->frun,
	(unsigned long long) cache->fcull,
	(unsigned long long) cache->fstop);

	stats.f_blocks >>= cache->bshift;
	do_div(stats.f_blocks, 100);
	cache->bstop = stats.f_blocks * cache->bstop_percent;
	cache->bcull = stats.f_blocks * cache->bcull_percent;
	cache->brun = stats.f_blocks * cache->brun_percent;

	_debug("limits {%llu,%llu,%llu} blocks",
	(unsigned long long) cache->brun,
	(unsigned long long) cache->bcull,
	(unsigned long long) cache->bstop);

	/* get the cache directory and check its type */
	cachedir = cachefiles_get_directory(cache, root, "cache");
	if (IS_ERR(cachedir)) {
	ret = PTR_ERR(cachedir);
	goto error_unsupported;
	}

	fsdef->dentry = cachedir;
	fsdef->fscache.cookie = NULL;

	ret = cachefiles_check_object_type(fsdef);
	if (ret < 0)
	goto error_unsupported;

	/* get the graveyard directory */
	graveyard = cachefiles_get_directory(cache, root, "graveyard");
	if (IS_ERR(graveyard)) {
	ret = PTR_ERR(graveyard);
	goto error_unsupported;
	}

	cache->graveyard = graveyard;

	/* publish the cache */
	fscache_init_cache(&cache->cache,
	&cachefiles_cache_ops,
	"%s",
	fsdef->dentry->d_sb->s_id);

	fscache_object_init(&fsdef->fscache, NULL, &cache->cache);

	ret = fscache_add_cache(&cache->cache, &fsdef->fscache, cache->tag);
	if (ret < 0)
	goto error_add_cache;

	/* done */
	set_bit(CACHEFILES_READY, &cache->flags);
	dput(root);

	pr_info("File cache on %s registered\n", cache->cache.identifier);

	/* check how much space the cache has */
	cachefiles_has_space(cache, 0, 0);
	cachefiles_end_secure(cache, saved_cred);
	return 0;

	error_add_cache:
	dput(cache->graveyard);
	cache->graveyard = NULL;
	error_unsupported:
	mntput(cache->mnt);
	cache->mnt = NULL;
	dput(fsdef->dentry);
	fsdef->dentry = NULL;
	dput(root);
	error_open_root:
	kmem_cache_free(cachefiles_object_jar, fsdef);
	error_root_object:
	cachefiles_end_secure(cache, saved_cred);
	pr_err("Failed to register: %d\n", ret);
	return ret;
	}

	/*
	* unbind a cache on fd release
	*/
	void cachefiles_daemon_unbind(struct cachefiles_cache *cache)
	{
	_enter("");

	if (test_bit(CACHEFILES_READY, &cache->flags)) {
	pr_info("File cache on %s unregistering\n",
	cache->cache.identifier);

	fscache_withdraw_cache(&cache->cache);
	}

	dput(cache->graveyard);
	mntput(cache->mnt);

	kfree(cache->rootdirname);
	kfree(cache->secctx);
	kfree(cache->tag);

	_leave("");
	}